Roll-mill for hard materials.



H. ALDEHOFF.

ROLL MILL FOR HARD MATERIALS.

APPLIGATION FILED 1111.19, 1914.

2 SHEETS-SHEET 1.

WITNESSES INVENTOR HERMANN ALDE HOFF BY ,l a ATTORNEYS Patented Mar. 23,1915.

H. ALDEHOFF.

ROLL MILL FOR HARD MATERIALS.

APPLICATION FILED JAN. 19, 1914.

L1 33 mm Patented Mar.23,1915

2 SHEETS-SHEET 2.

WITNESSES INVENTOR HERMANNALDEHOFF A TORNEYS HERMANN ALDEHOFF, 0FBERLIN, GERMANY.

ROLL-MILL For. HARD MATERIALS.

Application filed January 19, 1914.

To all whom it may concern Be it known that I, HERMANN ALDnnorF, asubject of the King of Prussia, residing at Berlin, in the Kingdom ofPrussia and German Empire, have invented new and useful Improvements inRoll-Mills for Hard Materials, of which the following is aspecification.

In roll-mills for hard material constructed on the Kent and MaXeconsystem the grinding ring is closed laterally by rings arranged at about5-10 mm. fromthe grinding ring. As the grinding ring in rotatlng movessomewhat laterally, a space of as much as 15 mm. can occur between oneside of the grinding ring and the corresponding disk. Through this spacepieces of 57 mm. and more can fall without being subjected to the actionof the rolls. For the purpose of lifting these pieces the millsheretofore used are provided with an elevator. With the object ofovercoming this drawback plates are secured to the sides of the grindingrlng, which plates nearly reach the shafts carrying the rolls and areprovided with perforations. These sieves have such a shape thatcircumferential mantle surfaces are formed, through which the materialpasses under the influence of the circumferential force.

In order to assure that the fine material leaves the mill behind thefirst roll and does not pass with the coarse material to the secondroll, where it would only impair the grinding action, a guide piece isprovided in the grinding ring behind the roll to Which the material isfirst led, said guide piece having a roof like shape as seen from theside, preferably also as seen from the front, and a wedge shaped frontend. The operation of this guide piece is explained below.

A mill constructed according to the 1nvention is shown by way of examplein the drawing.

Figure 1 is a vertical cross section, and Fig. 2, a verticallongitudinal section through the mill, Fig. 3 shows a pla n of the guidepiece arranged in the grlnding mill between the first and second rolls.

The grinding ring a; is carried by the uppermost roll 6 which serves asa friction roll and drives the ring. To the sides of the ring a areattached the plates 0, which from the grinding surface cl are bentinward and then parallel with the side flanges of the ring. These platesare perforated, 1n order to allow the fine ground material to passSpecification of Letters Patent.

Patented Mar. 23%, 1911.5.

Serial No. 813,045.

through. In order to better remove the fine material ventilators can beattached to the casing (2 outside of the plates 0. The guide piece fhasa roof-like cross section (Fig. 1), preferably also a rooflikelongitudinal sect1on (Fig. 2-), while its front end .9 has a wedgeshape. The wedge shaped end 9 conducts the material coming from thefirst roll b toward opposite sides, thus out of the grinding ring a intothe sieves c. As however these sieves are inclined the material notpassing through the same falls back agaln and thus arrives between thesecond roll 6 and the grinding ring. The fine material is also thrown bythe roll 6 onto the roofiike guide piece and is led by the form of thispiece to the sieves, through which 1t passes in order to leave themachine. The material falling from the roll 6 is also directed by theguide piece 1'' toward the sieves.

The wedge shaped front end 9 serves simultaneously as scraper to removeall material adhering to the grinding ring. The opposite end it of theguide piece 7 is adapted to the shape of the roll Z2 but need not touchthe same. The guide piece 7 is kept in position by lugs 2' having holesthrough which bolts 72 pass, the ends of which are secured to the sideplates of the casing.

The advantage of this mill will be clear from the fact that the existingmills of this kind have an output 0f 17 50 kilograms of finished cementper hour when 20,000 kilograms of raw material are passed through themill, while in the new mill an output of 3500 kilograms of finishedcement is obtained when only 10,000 kilograms of raw material are assedthrough the machine. This increase output is explained by the fact thatthe rolls and grinding ring are kept free from fine material, so thatthe material which is still coarse is not subjected to the grindingaction in a bed of fine material. A further advantage of the inven tionis that the transort apparatus has less material to deal wit 1, so thatless power is required.

What I claim and desire to secure by Letters Patent of the United Statesis 1. The grinding mill for hard materials, comprising in combination, agrinding ring, grinding rolls inside said grinding ring, sieve-platesattached to the sides of said grinding ring and bent to form acircumferential mantle, a guide piece inside said ring behind the firstof said grinding rolls,

said guide piece'having a roof shape in cross section and a wedge shapedfront end, substantially as, and for the purpose, set forth.

2. The grinding mill for hard materials,

' comprising in combination, a grinding ring,

grinding rolls inside said grinding ring, sieve-plates attached to thesides of said grinding ring and bent to form a circumferential mantle, aguide piece inside said ring behind the first of said rolls, said guidepiece having a roof shape in cross section,

a roof shape in longitudinal section and a wedgexshaped front end,substantially as, and for the purpose, set forth.

3. A grinding mill for hard materials, comprising a grinding ring, anupper grind- Copies of this patent may be obtained for five cents each,by addressing the Commissioner of Patents,

- Washington, D. G."

